JPH10134389A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely determine the optimum recording power value by OPC (optimum power control) by preventing incomplete erasure in PCA(power calibration area) SOLUTION: The PCA of an optical disk 4 is erased at multiple levels of erase power value by a controller 15; the peak and bottom values are detected of the reproducing signal from the PCA after the erasure; an amplitude is determined on the basis of these peak and bottom values; the erase power value at the time when the determined amplitude becomes smaller than a prescribed value is decided as the optimum erase power value for DC-erasing the PCA; and the PCA of the optical disk 4 is DC-erased at that optimum erase power value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus for recording and reproducing data on a rewritable optical disk such as a CD-E drive.

[0002]

2. Description of the Related Art A CD-E disk is formed by irradiating a laser beam having a large power value onto a track in a crystalline state to melt a recording film on a recording surface and then rapidly cooling the recording film to form a recording mark. When information is recorded, the information is erased by irradiating the recording mark with a laser beam having a smaller power value than that at the time of recording to crystallize the amorphous portion again (for example,
"Journal of the Japan Institute of Metals Vol.57 No.2 (1993) 22
8-232 ").

As described above, since the recording surface can be changed to an amorphous phase or a crystalline phase only by modulating the laser power value, new information is overwritten on the previously recorded information.
So-called overwriting is possible.

In such an optical disk apparatus for recording and reproducing information on a CD-E disk, when information is overwritten on the CD-E disk, the recording mark cannot be sufficiently formed if the erasing power value of the laser beam or the irradiation time is insufficient. Unerased parts remain without being completely erased. On the other hand, if the erasing power is too high, the melting point of the recording film will be approached, so that the amorphous crystallization will be slowed down and the erasing ratio will be reduced.

As described above, setting the optimum erasing power value is as important as setting the optimum recording power value so as not to degrade the quality of information recording and reproduction.

Conventionally, in an optical disk apparatus for recording and reproducing information on a CD-E disk, an optimum power control (OPC) is performed in a power calibration area (PCA) as a power calibration performed before recording the information. The PCA is all OPC
Since the PCA is rewritable even when used, the OPC for determining the optimum recording power value can be performed.

[0007]

However, in the above-mentioned conventional optical disk apparatus, if OPC is performed by the PCA without erasing data with the optimum erasing power, the OPC is performed on the PCA in which information remains unerased. Therefore, there is a problem that the accuracy of the optimum recording power value determined by OPC is reduced. The present invention has been made in view of the above points, and has as its object to prevent an unerased PCA and to accurately determine an optimum recording power value by OPC.

[0008]

According to the present invention, there is provided an optical disk apparatus for recording and reproducing data on and from a rewritable optical disk having a power calibration area for trial writing when obtaining an optimum recording power. Erasing the power calibration area with a plurality of levels of erasing power values, detecting a peak value and a bottom value of a reproduced signal from the power calibration area after the erasing, and based on the peak value and the bottom value. Means for obtaining an amplitude value and means for determining an erasing power value when the amplitude value obtained by the means is smaller than a predetermined value as an optimum erasing power value for DC erasing the power calibration area are provided. is there.

Further, in an optical disc apparatus for recording and reproducing data on and from a rewritable optical disc having a power calibration area for trial writing when obtaining an optimum recording power, the power calibration area is provided with a plurality of levels of erasing power values. Means for erasing, detecting a peak value and a bottom value of the reproduced signal from the power calibration area after the erasure, and obtaining an amplitude value based on the peak value and the bottom value; The change rate of the amplitude value when the erase power value is changed is determined based on the erase power value, and the erase power value when the change rate becomes equal to or less than a predetermined value is determined as the optimum erase power value for DC erasing the power calibration area. It is preferable to provide a means for performing this.

Further, in an optical disc apparatus for recording and reproducing data on and from a rewritable optical disc having a power calibration area for trial writing when obtaining an optimum recording power, the power calibration area is provided with a plurality of levels of erasing power values. Means for erasing, detecting a peak value and a bottom value of the reproduction signal from the power calibration area after the erasure, and obtaining a DC voltage value of the reproduction signal based on the peak value and the bottom value; It is preferable to provide a means for determining an erase power value when the DC voltage value becomes larger than a predetermined value as an optimum erase power value for DC-erasing the power calibration area.

Further, in an optical disc apparatus for recording and reproducing data on a rewritable optical disc having a power calibration area for trial writing when obtaining an optimum recording power, the power calibration area may have a plurality of levels of erasing power values. To erase,
Means for detecting a peak value and a bottom value of the reproduced signal from the power calibration area after the erasure, and obtaining an amplitude value based on the peak value and the bottom value; The erasing power value at which the amplitude value of the reproduced signal after erasing with the erasing power value becomes 0 is obtained by linear approximation, and the obtained erasing power value is determined as the optimum erasing power value for DC erasing the power calibration area. Means may be provided.

An optical disk device according to a first aspect of the present invention is:
Erasing the power calibration area for test writing when obtaining the optimum recording power of the rewritable optical disc with multiple levels of erasing power values, and then determining the peak value and bottom value of the reproduction signal from the power calibration area after the erasing. Detecting and calculating an amplitude value based on the peak value and the bottom value, and determining an erasing power value when the obtained amplitude value is smaller than a predetermined value as an optimum erasing power value for DC erasing the power calibration area. To decide.

Therefore, when DC erasing the power calibration area of the optical disk, it is possible to eliminate unerased recording marks with an optimum erasing power value.
The optimum recording power value by the PC can be accurately determined.

According to a second aspect of the present invention, there is provided an optical disk apparatus for erasing a power calibration area for trial writing at a plurality of levels of erasing power values when obtaining an optimum recording power of a rewritable optical disk. When the peak value and the bottom value of the reproduction signal from the power calibration area are detected, the amplitude value is obtained based on the peak value and the bottom value, and the erase power value is changed based on the obtained amplitude value. And the erase power value when the change rate becomes equal to or less than a predetermined value is determined as the optimum erase power value for DC erasing the power calibration area.

Therefore, when DC erasing the power calibration area of the optical disk, it is possible to eliminate unerased recording marks with an optimum erasing power value.
The optimum recording power value by the PC can be accurately determined.

Further, according to a third aspect of the present invention, the power calibration area for trial writing the optimum recording power of the rewritable optical disk is erased with a plurality of levels of erase power values, and the power calibration after the erase is performed. When the peak value and the bottom value of the reproduction signal from the area are detected, the DC voltage value of the reproduction signal is obtained based on the peak value and the bottom value, and the obtained DC voltage value becomes larger than a predetermined value. Is determined as the optimum erasing power value for DC erasing the power calibration area.

Therefore, when DC erasing the power calibration area of the optical disk, it is possible to eliminate unerased recording marks with an optimum erasing power value.
The optimum recording power value by the PC can be accurately determined.

Still further, according to the optical disk apparatus of the present invention, the power calibration area for trial writing the optimum recording power of the rewritable optical disk is erased with a plurality of levels of erasing power values, and the power calibration after erasing is performed. After detecting the peak value and the bottom value of the reproduction signal from the application area, obtaining the amplitude value based on the peak value and the bottom value, and erasing the data with a plurality of erasing power values of at least three or more points. The amplitude value of the reproduced signal is 0
Is obtained by linear approximation, and the obtained erasing power value is converted to the power calibration area by DC.
The optimum erasing power value to be erased is determined.

Therefore, the optimum erasing power value at the time of DC erasing the power calibration area can be quickly set, so that the process of setting the optimum erasing power value can be completed in a short time.

[0020]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of an optical disk device according to an embodiment of the present invention. FIG. 2 is a diagram showing a data format before writing data to a rewritable optical disk. FIG.
FIG. 3 is a diagram showing a data format after writing data to a rewritable optical disk. FIG. 4 is a diagram showing a PCA data format of a rewritable optical disk.

As shown in FIG. 1, this optical disc apparatus records and reproduces data on a rewritable optical disc 4 such as a CD-E disc having a power calibration area for trial writing when obtaining an optimum recording power. A spindle motor 1 for rotating the optical disk 4, an optical pickup 3 for irradiating the recording surface of the optical disk 4 with laser light, and an optical pickup 3
The coarse motor 2 is provided for moving the optical disc 4 in the radial direction of the optical disc 4.

A rotation control system 11, a coarse motor control system 12, and a pickup control system 1 realized by a microcomputer comprising a CPU, a ROM, a RAM, and the like.
3, a signal processing system 14 and a controller 15 are provided.

The rotation control system 11 controls the rotation of the spindle motor 1. The coarse motor control system 12 controls the driving of the coarse motor 2. The pickup control system 13 controls focusing and tracking of the optical pickup 3. The signal processing system 14 generates a focus error signal and a track error signal when the pickup control system 13 performs focusing and tracking control based on the signal from the optical pickup 3.

The controller 15 is connected to a host computer via an external interface, and controls the rotation control system 11, the coarse motor control system 12, and the pickup control system 1.
It controls the entire optical disk apparatus including the signal processing system 3 and the signal processing system 14, and performs various processes such as a DC erasing process of a power calibration area (PCA) and an OPC process of the PCA according to the present invention.

That is, the controller 15 or the like erases the power calibration area with a plurality of levels of erase power values, detects the peak value and the bottom value of the reproduced signal from the power calibration area after the erasure, and A means for obtaining an amplitude value based on the peak value and the bottom value, and an erasing power value when the amplitude value obtained by the means becomes smaller than a predetermined value as an optimum erasing power value for DC erasing the power calibration area. Acts as a means of determining.

Next, the format of a CD-E disk as an optical disk used in this optical disk device will be described. As shown in FIG. 2, the CD-E disc has an information area in which data can be actually written before data writing. After writing data in this information area, as shown in FIG. 3, a power calibration area (PCA), a program memory area (PMA), a lead-in area,
A program area and a lead-out area are formed.

The lead-in area and the lead-out area contain information on the recorded track.
The PCA is an area in which test writing is performed to obtain an optimum recording laser power value for recording data before data recording. The PMA is a borrowed TOC (table of contents) information recording area at the time of intermediate recording in a state where additional recording is possible. The program area is an area for recording data.

Next, the PCA will be described. As shown in FIG. 4, the PCA includes a test area and a count area. The test area is divided into 100 partitions, and one partition is used for each power calibration. The count area is divided into 100 partitions corresponding to each partition of the test area, and is recorded when each partition of the test area is used. This count area is used to search for unused test area partitions.

Next, DC erasing processing of the PCA of the optical disk in the optical disk apparatus will be described. FIG. 5 is a flowchart showing a DC erasing process of the PCA in the optical disk device shown in FIG. FIG. 6 is a diagram showing the relationship between the erase power value and the amplitude value of the reproduced signal in the DC erase process of the PCA shown in FIG.

As shown in FIG. 5, the initial setting of the erasing power value when the PCA is first erased starts with a power value larger than the read power value in step (indicated by "S" in the figure) 1. For example, since the read power value is 1 mW or less based on the Orange Book Part 3, the erase power value is gradually increased by 1 mW from the erase power value: P ₀ = 2 mW, and erase is performed.

The PCA to be erased to determine the optimum erase power value selects an arbitrary partition in the test area or the count area as shown in FIG.
Therefore, the erase power value initially set in step 2: P
After erasing the PCA at ₀ , the amplitude value of the residual reproduction signal: Vpp is calculated at step 3.

This residual reproduction signal amplitude value: Vpp is equal to PC
One partition of A is 15 ATIP frame length (15
/ 75 seconds), the peak value and the bottom value of the reproduced signal are obtained during this period, and the amplitude value: V
Calculate pp.

Thereafter, in step 4, it is determined whether or not the amplitude value: Vpp is smaller than a predetermined value: Vth. This predetermined value: Vth is the upper limit value of the amplitude value of the reproduction signal corresponding to the erasing power value that does not cause unerasing when erasing the PCA. Amplitude value: Vp as determined in step 4
If p is greater than or equal to the predetermined value: Vth, the process proceeds to step 7 where the erasing power value is increased, and erasing is again performed using the PCA erased in step 2.

Also, in the judgment of step 4, the amplitude value: Vpp
Is smaller than the predetermined value: Vth, the program proceeds to step 5 where the erase power value at that time is determined and set as the optimal erase power value, and the program proceeds to step 6 to execute DC erasure of the PCA by the optimal erase power value. I do.

For example, as shown in FIG. 6, the erasing power value: Pe = 10 mW, starting from the erasing power value: P ₀ = 2 mW.
The amplitude value is gradually increased to mW, and the amplitude value is obtained based on the peak value and the bottom value of each reproduction signal. Then, as shown in the figure, the amplitude value: Vpp = V ₀ when the erasing power value: P ₀ = 2 mW gradually decreases, and when the erasing power value: Pe = 10 mW, the predetermined value:
An amplitude value smaller than Vth: Vpp = Ve. Therefore, this erase power value: Pe = 10 mW is determined as the optimum erase power value.

Therefore, when DC erasing the power calibration area of the optical disk, it is possible to eliminate unerased recording marks with an optimum erasing power value.
The optimum recording power value by the PC can be accurately determined.

Next, another example of the DC erasing process of the PCA of the optical disk in the optical disk device will be described. In this case, the configuration of the optical disk device is the same as that of the optical disk device shown in FIG.
Are different from those described above, and the processing for determining the optimum erasing power value is different from the processing described above.

That is, the controller 15 or the like erases the power calibration area with a plurality of levels of erase power values, detects the peak value and the bottom value of the reproduced signal from the power calibration area after the erasure, and Means for obtaining an amplitude value based on the peak value and the bottom value, and a change rate of the amplitude value when the erasing power value is changed based on the amplitude value obtained by the means, and the change rate becomes equal to or less than a predetermined value. The function of deciding the erase power value at the time of becoming the optimum erase power value for DC erasing the power calibration area is performed.

Next, the D of the PCA of the optical disk in this case is
The C erasing process will be described. FIG. 7 shows the DC of the PCA.
It is a flowchart figure which shows an erasing process. FIG. 8 is a diagram showing the relationship between the erase power value and the amplitude value of the reproduced signal in the DC erase process of the PCA shown in FIG. FIG. 9 shows FIG.
FIG. 7 is a diagram showing changes in calculation results based on the erase power value and the amplitude value of the reproduction signal shown in FIG.

As shown in FIG. 7, in step 11, an initial erasing power value: Pi is set, and the program proceeds to step 12, where the PCA is erased with the erasing power value: Pi. Is calculated.
Next, proceeding to step 14, similarly, setting an erasing power value: Pi + 1 (≧ Pi), proceeding to step 15, and erasing the PCA, proceeding to step 16, and proceeding to step 16, the amplitude value of the residual reproduction signal: Calculate Vi + 1.

Thereafter, from the amplitude values Vi and Vi + 1 of the residual reproduction signal at the erasing power values Pi and Pi + 1, a change rate of the amplitude value of the reproduction signal when the erasing power value is changed is obtained by the following equation (A). | (Vi + 1−Vi) / (Pi + 1−Pi) | (A)

Then, the process proceeds to a step 17, wherein it is determined whether or not the rate of change obtained by the equation (A) is smaller than a predetermined value: α. The predetermined value α is an upper limit of a change value obtained from an erasing power value that does not cause unerasing when erasing the PCA and the amplitude value of the reproduction signal corresponding to the erasing power value. If the rate of change is equal to or greater than the predetermined value α in the determination of step 17, the process proceeds to step 20 where the erase power value is increased to
It is set to i + 2 and erased again with the PCA erased in step 15.

If the rate of change is smaller than the predetermined value α in the determination of step 17, the program proceeds to step 18 where the erase power value at that time is determined and set as the optimum erase power value, and the program proceeds to step 19. The DCA of the PCA is executed using the optimum erasing power value.

[0044] For example, as shown in FIG. 8, an erasing power value: Pe = beginning P ₁ erasing power value: Pe = Pi +
Then, the amplitude value is obtained based on the peak value and the bottom value of each reproduction signal. Then
As illustrated, the erase power value: Pe = amplitude value when the P _1: Vpp = V ₁ gradually decreases, erasing power value:
When Pe = Pi + 1, the amplitude value is Vpp = Vi + 1.

From the amplitude value thus obtained and the erase power value, the change rate of the amplitude value when the erase power value is changed based on the equation (A) is obtained. become. Then, an erasing power value corresponding to a change rate smaller than a predetermined value: α is determined as an optimum erasing power value. In this case, two erasing power values: Pi and P
Since i + 1 corresponds, Pe =
(Pi + Pi + 1) / 2.

Therefore, when DC erasing the power calibration area of the optical disk, it is possible to eliminate unerased recording marks with an optimum erasing power value.
The optimum recording power value by the PC can be accurately determined.

Next, still another processing example of the DC erasing processing of the PCA of the optical disk in the optical disk apparatus will be described. In this case, the configuration of the optical disk device is the same as that of the optical disk device shown in FIG. 1, but the functions of the controller 15 and the like are different from those described above, and the process of determining the optimum erasing power value is different from any of the above-described processes.

That is, the controller 15 or the like erases the power calibration area with a plurality of levels of erase power values, detects the peak value and the bottom value of the reproduced signal from the power calibration area after the erasure, and DC of reproduced signal based on peak value and bottom value
The function of the means for determining the voltage value and the means for determining the erasing power value when the DC voltage value obtained by the means becomes greater than a predetermined value as the optimum erasing power value for DC erasing the power calibration area. .

Next, the DC erasing process of the PCA of the optical disk in the optical disk device will be described. FIG.
FIG. 4 is a flowchart showing the DC erasing process of the PCA. FIG. 11 is a diagram showing a change in a reproduction signal from a track on which data is not recorded in the DC erasing process of the PCA shown in FIG. FIG. 12 shows the DC of the PCA shown in FIG.
FIG. 11 is a diagram showing a change in a reproduction signal after erasing a track on which data has been recorded in an erasing process. FIG. 13 shows FIG.
FIG. 13 is another diagram showing a change in a reproduction signal after erasing a track on which data has been recorded in the DC erasing process of the PCA shown in FIG.

As shown in FIG. 10, the initial erasing power value: P ₀ is set in step 21 and the PCA is erased in step 22. Then, the process proceeds to step 23 in which the DC voltage va of the residual reproduction signal is reduced. calculate.

Before explaining the processing for obtaining the DC voltage: va of the reproduction signal, the reproduction signals of the track on which the data is not recorded and the track on which the data shown in FIGS. An example of the result when monitoring with an oscilloscope is shown. First, in the case of group recording, a track on which no data is recorded corresponds to a track shown in FIG.
As shown in FIG. 1, a voltage corresponding to the reflectance of the group: I
g.

However, when data is recorded, as shown in FIG. 12, a waveform is obtained in which the reflectance of only the recording mark portion is low. The waveform shown in FIG. 12 shows a case where the erasing power value is insufficient and data remains unerased. When the erasing power value is further increased, the waveform shown in FIG. 13 is obtained.

When data is erased with the optimum erase power value, it is desirable that the waveform shown in FIG. 11 be obtained. Therefore, as shown in FIG. 12, the erasing power value: P ₀
As the DC voltage: Va of the reproduced signal erased by
An intermediate value (intermediate voltage) between the peak value and the bottom value obtained by Va = (Vp + Vb) / 2.

Returning to the flow of FIG. 10, in the calculation of the DC voltage va of the residual reproduction signal in step 23, Va = (Vp + Vb) / 2 as described above. Then, the process proceeds to a step 24, wherein it is determined whether or not the DC voltage: va is larger than a predetermined value: β. This predetermined value: β is the lower limit value of the DC voltage value obtained based on the peak value and the bottom value of the reproduction signal from the PCA after erasing with the erasing power value that does not cause unerasing when erasing the PCA.

If the DC voltage: va is equal to or smaller than the predetermined value: β in the judgment of step 24, the flow advances to step 27 to further increase the erasing power value, and then returns to step 22. If the DC voltage: va is larger than the predetermined value: β,
5, the erase power value at that time is determined and set as the optimum erase power value.
Perform erasure.

Therefore, when DC erasing the power calibration area of the optical disk, it is possible to eliminate unerased recording marks with an optimum erasing power value.
The optimum recording power value by the PC can be accurately determined.

Next, still another DC erasing process of the PCA of the optical disk in the optical disk device will be described. In this case, the configuration of the optical disk device is the same as that of the optical disk device shown in FIG.
The functions such as 5 are different from those described above, and the processing for determining the optimum erasing power value is different from any of the above-mentioned processings.

That is, the controller 15 or the like erases the power calibration area with a plurality of levels of erase power values, detects the peak value and the bottom value of the reproduced signal from the power calibration area after the erasure, and Means for obtaining an amplitude value based on the peak value and the bottom value, and linearly approximating an erasing power value at which the amplitude value of the reproduced signal after erasing with a plurality of erasing power values of at least three points obtained by the means becomes zero. And the obtained erasing power value is set in the power calibration area by D
It functions as a means for determining the optimum erase power value for C erase.

Next, the DC erasing process of the PCA of the optical disk in the optical disk device will be described. FIG.
FIG. 3 is a diagram showing a linear approximation of an erasing power value by the DC erasing process of the PCA.

In this process, the PCA is erased with a plurality of levels of erase power values, the peak value and the bottom value of the reproduced signal from the PCA after the erasure are detected, and the amplitude value is determined based on the peak value and the bottom value. Ask for. Thereafter, an erasing power value at which the amplitude value of the reproduced signal after erasing with the plurality of erasing power values of at least three or more points becomes 0 is obtained by linear approximation, and the obtained erasing power value is converted to a DCA by DCA. The optimal erasing power value to be erased is determined and set.

For example, as shown in FIG.
Erase power values P ₀ , P ₁ , P ₂ (P ₀ <P ₁ <P
_When the amplitude value of the reproduced signal after erasing in step ₂ ): Vpp becomes V ₀ , V ₁ , and V ₂ , respectively, these points are linearly approximated, and the optimum erasing power value becomes Vpp = 0. If it is defined as a value, an optimum erasing power value: Pe can be obtained.

Therefore, when DC erasing the power calibration area of the optical disk, it is possible to eliminate unerased recording marks with an optimum erasing power value.
Since the optimum recording power value by the PC can be accurately determined, and the optimum erasing power value can be set quickly, the setting process of the optimum erasing power value can be completed in a short time.

[0063]

As described above, according to the optical disk apparatus of the present invention, it is possible to prevent the unerased PCA and determine the optimum recording power value by the OPC with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an optical disk device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a data format before writing data to a rewritable optical disc.

FIG. 3 is a diagram showing a data format after writing data to a rewritable optical disk.

FIG. 4 is a diagram showing a PCA data format of a rewritable optical disk.

FIG. 5 is a flowchart showing a PCA DC erasing process in the optical disk device shown in FIG. 1;

6 is a diagram showing a relationship between an erasing power value and an amplitude value of a reproduction signal in a DC erasing process of the PCA shown in FIG. 5;

FIG. 7 is another PC in the optical disk device shown in FIG.
FIG. 9 is a flowchart illustrating a DC erasing process of A.

8 is a diagram showing a relationship between an erasing power value and an amplitude value of a reproduction signal in the DC erasing process of the PCA shown in FIG. 7;

FIG. 9 is a diagram illustrating a change in a calculation result based on the erase power value and the amplitude value of the reproduction signal illustrated in FIG. 8;

FIG. 10 is a flowchart illustrating a DC erasing process of still another PCA in the optical disc device illustrated in FIG. 1;

11 is a diagram illustrating a change in a reproduction signal from a track on which data is not recorded in the DC erasing process of the PCA illustrated in FIG. 10;

12 is a diagram showing a change in a reproduction signal after erasing a track on which data has been recorded in the DC erasing process of the PCA shown in FIG. 10;

13 is another diagram showing a change in a reproduction signal after erasing a track on which data is recorded in the DC erasing process of the PCA shown in FIG. 10;

FIG. 14 is a diagram showing a linear approximation of an erasing power value by a DC erasing process of still another PCA in the optical disk device shown in FIG. 1;

[Explanation of symbols]

 1: Spindle motor 2: Coarse movement motor 3: Optical pickup 4: Optical disc 11: Rotation control system 12: Coarse movement motor control system 13: Pickup control system 14: Signal processing system 15: Controller

Claims (4)

[Claims] 1. An optical disc apparatus for recording and reproducing data on and from a rewritable optical disc having a power calibration area for trial writing when obtaining an optimum recording power value, wherein the power calibration area has a plurality of levels of erasing power values. Means for detecting a peak value and a bottom value of a reproduced signal from the power calibration area after the erasure, and obtaining an amplitude value based on the peak value and the bottom value; and an amplitude value obtained by the means. Means for determining an erasing power value when is smaller than a predetermined value as an optimum erasing power value for DC erasing the power calibration area. 2. An optical disc apparatus for recording and reproducing data on and from a rewritable optical disc having a power calibration area for trial writing when obtaining an optimum recording power, wherein the power calibration area has a plurality of levels of erase power values. Means for erasing, detecting a peak value and a bottom value of the reproduced signal from the power calibration area after the erasure, and obtaining an amplitude value based on the peak value and the bottom value; The change rate of the amplitude value when the erase power value is changed based on the
Means for determining an erasing power value when the rate of change is equal to or less than a predetermined value as an optimum erasing power value for DC erasing the power calibration area. 3. An optical disc apparatus for recording and reproducing data on and from a rewritable optical disc having a power calibration area for trial writing when obtaining an optimum recording power, wherein the power calibration area has a plurality of levels of erase power values. Means for erasing, detecting a peak value and a bottom value of the reproduction signal from the power calibration area after the erasure, and obtaining a DC voltage value of the reproduction signal based on the peak value and the bottom value; DC
Means for deciding an erasing power value when the voltage value becomes larger than a predetermined value as an optimum erasing power value for DC erasing the power calibration area. 4. An optical disc apparatus for recording and reproducing data on and from a rewritable optical disc having a power calibration area for trial writing when obtaining an optimum recording power, wherein the power calibration area has a plurality of levels of erase power values. Means for erasing, detecting a peak value and a bottom value of the reproduced signal from the power calibration area after the erasure, and obtaining an amplitude value based on the peak value and the bottom value; An erasing power value at which the amplitude value of the reproduced signal after erasing with the plurality of erasing power values becomes 0 is obtained by linear approximation, and the obtained erasing power value is set in the power calibration area by D.
Means for determining an optimum erasing power value for C erasing.